Expression and Activity of Recombinant Human Glutamate Decarboxylase 65 / 中国生物工程杂志

Human glutamate decarboxylase 65(hGAD65) is an enzyme that catalyzes the transformation of L-glutamic acid into ?-aminobutyric acid.It has been found that Type 1 diabetes mellitus(T1DM)is an autoimmune disease,in which pancreatic islet ?-cells are destroyed due to immune response mediated by autoantigen.hGAD65 is considered as a key autoantigen of the autoimmune response,so anti-hGAD65 antibody(hGAD65-Ab) is the most effective and specific immune marker for T1DM diagnosis,and hGAD65 can be used to detect hGAD65-Ab in serum of T1DM patients.The hGAD65 gene was cloned into pET32a(+),then the recombinant plasmid with hGAD65 was transformed into E.coli BL21(DE3) and expressed by IPTG induction.The fusion protein containing thioredox,hexahistidine and hGAD65(Trx-hGAD65) was mostly insoluble,but the band of soluble Trx-hGAD65 could also be detected by SDS-PAGE,and it was a great improvement compared with the results reported.Trx-hGAD65 was isolated from lysate and purified by immobilized metal ion affinity chromatography(IMAC).After enterokinase digestion and IMAC purification,hGAD65 with high purity was obtained.Detection of thin-layer chromatography(TLC) showed that both Trx-hGAD65 and hGAD65 had enzymatic activity,whereas Trx-hGAD65 had better stability.Furthermore,it was confirmed that Trx-hGAD65 was able to conjugate with hGAD65-Ab in the serum of T1DM patients by ELISA assay.In conclusion,Trx-hGAD65 instead of hGAD65 can be used for T1DM diagnosis,and its application in prophylaxis and therapy of T1DM is expectable.

Enhance the Expression of B. subtillis Fibrinolysis Enzyme by degQ Gene / 微生物学通报

The degQ gene, amplified from Bacillus subtilis by PCR, was cloned to pUBS (sucrose induced secretion vector). After transformed into DB403, recombination named DB403(pUBSD) was formed. The results of the fermentation showed that degQ gene enhanced the expression of B. subtilis fibrin enzyme. The activity of the enzyme was increased to 2.2 times as the original one. In this article, the effects of different conditions, such as different kinds of sugar, different concentration of sucrose and different induced time were also be investigated and compared.